This invention relates to the arts of medicine and chemistry and more particularly to a pliable centrifuge tube array.
A centrifuge is a device used to separate constituents of a sample according to density by generating artificial high "gravity" using centrifugal force. A typical centrifuge has a rotor which is spun at high speed by a motor. The rotor has recesses or slots ("wells") for receiving tubes containing samples to be separated. In rotors where the wells angle downward and outward, the dense material settles out toward one the side of the tube, near the bottom, forming what is known as a "pellet". It is best that the pellet be to one side, so that an aspirating pipette inserted along the opposite side will be sure to avoid interfering with the pellet.
Many current laboratory procedures involve repetitive centrifugation and resuspension in solution of individual samples of cells or extracts of cells: DNA, RNA, proteins, lipids, etc. The samples are spun in a centrifuge, then the supernatant liquid is aspirated off the pellet, another solution is added to the tubes, and the samples are spun again. This procedure may be repeated several times.
To improve processing speed, linear arrays of plastic tubes have been molded with the tubes interconnected along their sides. The axes of the tubes in such an array are parallel. Such tube arrays are convenient to handle, and by providing a constant predetermined centerline spacing, work well with automatic tube filling and sampling equipment such as multi-channel pipettes.
Parallel tube arrays have the problem that, when they are placed in a centrifuge, only one of the tubes can be located in a radial plane of the rotor. For any tube not in a radial plane, the "downward" direction in which the heavy constituents move is toward one side of the tube. Thus, the pellets of dense material which develop in such tubes wind up at various spots on the sides of the tubes. That is, the pellets are splayed away from each other in their location. The variation in pellet location makes it difficult to avoid consistently the pellets when aspirating liquid from the tubes. This problem is worse in an automated system where the pellet must be located by referring to a landmark on the tube.
In order for each tube to lie, properly, in a radial plane of the centrifuge rotor, and to get consistent pellet placement, the tubes must be able to diverge or splay outward.
Another disadvantage of conventional micro-centrifuge tube is that it has only a small outer surface on which the tube may be marked. Typically, the experimenter applies a number, and matches that number to a description in a notebook. This system is cumbersome: sometimes there is confusion as to what experiment the number refers to, especially after the tubes have been in storage for a while. It would be better to maintain tubes in united arrays which could be identified as a unit, and to provide a tube rack which could be marked upon as well.